Impact absorbing protective headgear



Aug. 26, 1969 R. c. SCHNEIDER ET AL 3,462,763

IMPACT ABSORBING PROTECTIVE HEADGEAR 3 Sheets-Sheet 1 Filed Oct. 5, 1967INVENTORS ichard C .Schneider,

g n n 0 Y 0 M nm J R m n T V A w E 2 3 Aug. 26, 1969 c SQHNElDER ET AL3,462,763

IMPACT ABSORBING PROTECTIVE HEADGEAR Filed Oct. 5, 19s? a Sheets-Sheet 2INVENTORS Richard C. Schneider,

and

Elwyn R. Gooding g- 1969 R. c; SCHNEIDER ETAL 3,462,763

IMPACT ABSORBING PROTECTIVE HEADGEAR Filed Oct. 5, 1967 3 Shams-Sheet 5INVENTORS Richard C. Schneider,

and

Elwyn RyGooding I wwjgw ATTORNE United States Patent 3,462,763 IMPACTABSORBING PROTECTIVE HEADGEAR Richard C. Schneider, 2110 Hill St. 48104,and Elwyn R. Gooding, 98 Valhalla Drive 48103, both of Ann Arbor, Mich.

Filed Oct. 3, 1967, Ser. No. 672,561 Int. Cl. A421) 1/08 U.S. Cl. 2-3 8Claims ABSTRACT OF THE DISCLOSURE A protective headgear assemblyconsisting of an impact absorbing and distributing outer shell and amulticellnlar inflatable inner support crown therefor positioned insurface-to-surface engagement with and secured to the outer shell. Theinner support crown is formed of a yieldable resilient material andconsists of a plurality of air or inert gas filled chambers which engageselected areas of the Wearers head. The inner support crown ispositioned between the outer shell and the wearers head so that forcesapplied to the outer shell are transmitted to the head only through theyieldable inner support crown. The outer shell has relatively firmsections which function like a frame and cover critical brain areas andmore resilient sections which cover less critical brain areas and willyield to an impact force so as to absorb and distribute the force beforeit is transmitted to the wearers head. An impact absorbing inflatablechin cup with an adjustable and self-retractable chin strap, all formedof a yieldable resilient material is secured with suitable fasteners tothe above protective headgear.

Background of the invention The protective headgear of this invention isuseful as a helmet for athletic participants, construction workers,electrical linemen, firemen, police, rescue squads, miners, mountainclimbers, skiers, motorcyclists, motor vehicle operators and occupants,sky divers, aircraft personnel, armed forces personnel and the like. Therigid plastic and metal helmets, which are presently being used by suchpeople, are usually mounted on various types of suspension systems thatengage the wearers head and are not adequate for preventing headinjuries. U.S. Patent 2,250,275 illustrates a type of football helmetwhich is presently being used extensively. Such a helmet consists of arigid outer shell mounted by means of rivets on an inner multiple strapsuspension system. The straps are usually formed of non-stretchablefabric material and engage the head of the wearer with line or pointcontact so that any impact from blows applied to the outer shell isdirectly transmitted to the head of the wearer with little diminution ofthe force of impact. Another type of protective headgear used as afootball helmet employs a composite padding type liner. Such a liner isvery slow in effecting any distribution of the shock energy applied tothe helmet so that as a result blows applied to the helmet aresubstantially directly transmitted to the wearers head. In addition,such helmets are objectionable because they are very heavy and tend toaffect the balance and movement of the head of the wearer. U.S. Patent2,150,290

' illustrates a helmet with inflatable cushions spaced from a fibreboard outer shell. An inner tube type cushion is secured to anon-stretchable material ring which is secured to the outer shell so asto hold the outer shell in a spaced relationship to the cushion. Animpact force applied to the outer shell causes it to move with abouncing ball action on the wearers head and thereby induce a rebound ofthe brain within the skull. Due to a lack of resiliency of the outershell and the inability of the present suspension systems to absorb theforce of such impact, there is a transmission of such force to theintracranial contents perhaps resulting in the tearing of blood vesselswith fatal hemorrhage or destruction of the brain.

It is an object of the present invention, therefore, to provide aprotective headgear assembly constructed specifically on the basis of ananatomical knowledge of the skull, intracranial membranes and brain andan understanding of the mechanical principles involved in head injuriescoupled with an extensive experience in the adaptation of variousmaterials to accomplish the desirable distribution and absorption ofimpact forces applied thereto to thereby reduce brain damage due to headinjuries.

Summary of the invention It has been found that the worst damage to thebrain occurs in those closed head injuries in which skull fracture doesnot occur. There is no dissipation of the impact of the blow but thereis a direct transmission of the force to the underlying area of thebrain or to the opposite side of the head resulting in a contre coupinjury (that is, damage to the skull or brain on the side opposite theside of the blow). In closed head injuries where fracture occurs thereis some dissipation of the force of the blow as the bone breaksresulting in less damage to the underlying brain than if the skull hadnot been fractured. The protective headgear assembly of this inventionconsists of an initial impact force absorbing and distributing outershell and an impact force distributing and absorbing multicellularinflatable inner support crown therefor which coact to absorb impactforces and distribute these forces throughout an extensive area of theheadgear assembly so as to minimize the localized forces applied to thewearers head. The outer shell has areas provided with relativelydifferent degrees of resiliency. Some sections of the outer shellconstitute firm sections and these cover and protect critical brainareas where damage is most likely to cause neurologic disability, andother sections of the outer shell constitute more resilient sections andthese cover the relatively silent areas of the brain. When positioned ona wearers head, the outer shell firm section has an annular portionwhich overlies and protects the inferior and posterior walls of the bonyfrontal sinus, the dural lateral sinuses and confluens at the base ofthe skull. This annular section is positioned at the back of the wearershead substantially above the cervical spine to avoid having this part ofthe protective headgear outer shell driven into the cervical spinecausing severe cervical hyperextension injuries which result in cervicalfractures or spinal cord damage. The firm section of the outer shellalso includes a medial arcuate strip which runs longitudinally of theprotective headgear in a direction fore and aft of the wearers head,overlying the longitudinal sinus and bridging veins, and arcuate stripswhich run transversely of the protective headgear overlying the brainmotor strips. The resilient sections are bounded by the firm sections soas to form arcuate shaped quadrants in the outer shell which overlie therelatively silent areas of the brain, namely, those regions of the brainwhich might absorb some stress without danger of as much residualneurologic deficit. These resilient sections of the helmet are thuscapable of yielding and deforming under the force of a blow so as toabsorb the initial impact of the blow, distribute the resultant force tothe surrounding firm sections and not transmit it directly to the brain.

The protective inner support crown is removably mounted on the innersurface of the outer shell so as to be disposed circumferentiallybetween the outer shell and the wearers skull. The inner support crownis preferably formed of a resilient yieldable plastic which can be airor inert gas inflated to the desired degree and which consists of aplurality of inflated chambers or cells. These chambers or cells arelocated in protective relation relative to the brain and are arranged sothat when an impact force is applied to any area of firm portion of theouter shell it is quickly distributed throughout the outer shell framestructure and transmitted to the multicellular inner support crown whichinstantaneously reacts to absorb the forces applied, throughout itsentirety. This construction of the protective headgear assembly alsoprovides for absorption of noise resulting from impact blows to theouter shell, so as to eliminate undesirable noises such as reverberationof sound resulting in ringing in the ears which is relatively common inprotective headgears now in use.

Further objects, features and advantages of this invention will becomeapparent from a consideration of the following description, the appendedclaims, and the accompanying drawings in which:

FIGURE 1 is a pictorial perspective cutaway view of one embodiment ofthe protective headgear assembly of this invention, illustrating thephysical relationship of the protective headgear assembly to the headand important intracranial contents of the wearer;

FIGURE 2 is a side elevational view of the protective headgear assemblyshown in FIG. 1, illustrating the protective headgear assembly securedin position on the head of a wearer with an impact absorbing inflatablechin cup and an adjustable and self-retractable chin strap;

FIGURE 3 is a top plan view of the protective headgear assembly shown inFIG. 1;

FIGURE 4 is a front elevational view of the protective headgear assemblyshown in FIG. 1, showing the assembly mounted on the head of a wearer;

FIGURE 5 is a bottom plan view of the protective headgear assembly shownin FIG. 1, with the chin cup and chin strap removed;

FIGURE 6 is an enlarged longitudinal sectional view of the protectiveheadgear assembly as seen from substantially the line 66 of FIG. 3;

FIGURE 7 is a perspective view of the impact absorbing multicellularinflatable inner support crown in the protective headgear assembly ofthis invention shown in FIG. 1;

FIGURE 8 is a perspective view of an impact absorbing multicellularinflatable temporal, aural and mandibular element in the protectiveheadgear assembly of this invention;

FIGURE 9 is a fragmentary sectional view of a portion of the protectiveheadgear assembly of this invention depicting relative thicknesses ofdifferent areas of the impact absorbing and distributing outer shell andan impact distributing and absorbing multicellular inflatable innersupport crown in exaggerated style for purpose of illustration;

FIGURE 10 is a fragmentary sectional view illustrated similarly to FIG.9, showing the inner support crown detached from the outer shell;

FIGURE 11 is a sectional view like FIG. 10, showing a modified form ofinner support crown in the protective headgear assembly of thisinvention;

FIGURE 12 is a transverse sectional view of a portion of the innersupport crown as seen from substantially the line 1212 in FIG. 7;

FIGURE 13 is a sectional view, like FIG. 12, illustrating a modifiedform of the inner support crown in the protective headgear assembly ofthis invention; and

FIGURE 14 is a fragmentary detailed sectional view of a portion ofanother form of the protective headgear assembly of this invention asformed to adapt it for a construction worker or the like.

With reference to the drawing, the protective headgear assembly of thisinvention, indicated generally at 10, is illustrated in FIG. I mountedon the head 12 of an athlete such as a football player. The protectiveheadgear assembly 10 consists of an outer shell 14 and a yieldable innersupport crown 16 which is removably mounted on the inner surface 18 ofthe shell 14 in a manner to be described in detail hereinafter and animpact absorbing inflatable chin cup with an adjustable andself-retractable chin strap.

The outer shell 14, which in the illustrated embodiment of the inventionshown in FIG. 1, is preferably molded from a resilient plastic materialso as to be of one piece, is provided with a section 20 which isrelatively firm and sections 22 of relatively greater resiliency, sothat sections 20 and 22 are hereinafter sometimes referred to as firmand resilient sections, respectively. In the illustrated embodiment ofthe invention, these sections 20 and 22 are provided with relativelydifferent degrees of resiliency by making the section 20 of increasedthickness relative to the section 22. In a preferred embodiment of theinvention, the material for the impact absorbing and distributing outershell is a polymer blend of acrylonitrile-butadiene-styrene, suchmaterial being commonly known as ABS material.

The firm section 20 is designed to overlie either the areas of theskull, which might fracture, or cover specific portions of theintracranial contents, which most frequently are damaged in headinjuries. The firm section 20 includes an annular portion 24 which, whenthe headgear assembly 10 is mounted on the head 12, encircles the headand is positioned in a protective covering relation with the inferiorand posterior Walls of the bony frontal sinus 26 in the skull 28 of thehead 12.

The firm annular portion 24 covers the branches of the middle meningealartery 42 which is captive in a bony groove of the thin temporal bone.If these vessels are transected with or without a fracture of the skull,the result is a hemorrhage on the surface of the membrane surroundingthe brain (i.e., an extradural hemorrhage). The annular portion protectsthe lateral sinuses 46 and the site at which they join the longitudinalsinus 48 to form a reservoir (i.e., the confluens of the sinuses ortorcula Herophili) Which must be protected for they are a source ofextradural hemorrhage, although they are less frequently a cause thanthe middle meningeal artery. The portion 24 also protects the base ofthe skull 28 directly behind the frontal sinus 26 (i.e., the cribiformplate) which may be very thin and, if fractured, bone fragments may tearthe membranes of the brain permitting a leakage of watery fluid (thecerebrospinal fluid which bathes the brain) providing a pathway forinfection with the possibility of meningitis or a brain abscess. Theouter shell 14 is shaped so that the portion 24 has its posterior edge30 (FIG. 2) positioned above and in a clearance relation with thewearers cervical spine 32. In other words, the rear edge 30 of theheadgear assembly 10 is positioned high on the wearers head to avoid theguillotine effect of this part of the protective headgear assembly outershell 14 being driven into the cervical spine 32 causing severehyperextension injuries which result in cervical fractures or spinalcord damage.

The outer shell firm section 20 also includes an elongated arcuate stripportion 34 which extends medially fore and aft of the protectiveheadgear assembly 10 and the head 12 and is integral at its ends to theannular portion 24. The strip firm portion 34 also protects thelongitudinal sinus 48 and the bridging vein which drain the blood fromthe upper surface (vertex 50) of the brain into the longitudinal sinus.These bridging vein are thinwalled and are the most frequent source ofbleeding underneath the membranes which encircle the brain (i.e.,subdural hemorrhage). The firm section at the top of the protectiveheadgear outer shell also overlies and protects the parietal brain area51. Firm curvate side strip portions 36 extend from the top of the outershell 14 in a downwardly and forwardly direction, as seen in FIG. 2, andare integral at their lower ends with the annular portion 24. These firmportions overlie and protect the motor strip areas 40 of the brain. Theremaining sections of the outer shell 14 are the resilient sections 22which are thus of arcuate quadrant shape and are bounded by the firmportions 24, 34 and 36.

The firm section 20 of the outer shell 14 also includes vertical sideportions 52 which extend downwardly from the annular portion 24bilaterally, overlying and protecting the temporal, aural and mandibularareas. Circular openings 54 are provided in the sections 52 to coincidewith the aural canals 56 and external ears of the wearer to facilitatehearing. The vertical side sections 52 are designed to resist horizontalinward movement of the outer shell 14 and also provide a firm anchor fora chin strap 59 secured at its ends to the vertical side portions 52.Air circulating holes 68 are located in the firm strip portions 24, 34and 36 of the outer shell 14 so as to be adjacent the inner supportcrown 16 and create a positive air circulation throughout the protectiveheadgear assembly 10, thereby reducing perspiration of the head thusalleviating the possibility of an upset in the electrolyte balance ofthe body and affording greater comfort to the wearer. As shown in FIGS.1 through 6, inclusive, the outer shell 14 has no ridges, bumps,protrusions, projections or irregularities or its external surface and aTeflon plastic coating can be readily applied to the entire outersurface of the outer shell, thereby providing a surface with as low acoefficient of friction as possible to permit the protected head to seekthe path of least resistance on impact and thereby lessen thepossibility of torsional injury, namely, injury to the head 12 due totwisting of the protective headgear assembly 10.

It can thus be seen that the firm section 20 of the shell 14 is shapedto conform to the head 12 so as to overlie and protect the vertex 50 andextend downwardly in all directions over the parietal brain area 51, thefrontal brain area 53, the temporal brain area 44, the occipital brainarea 55 and including the mandibular, the aural canal 56 and the earbilaterally. As shown in FIG. 2, the annular portion 24 increases inwidth in a front to rear direction for this important purpose. Theresilient sections 22 cover the relatively silent brain areas 57 atpositions between the firm portions.

The yieldable resilient inner support crown 16 functions to dissipateforces applied to the outer shell 14 over a large area so as to preventthe transmission of localized impact forces to the wearers head 12. Thesupport crown 16 is formed of a yieldable resilient material, and in apreferred embodiment of the invention this material is a vinylplastisol. Design configurations incorporating various combinations ofwall thicknesses, durometers and elasticity can be readily employed toobtain the desired degree of resilience in the support crown 16 to adaptthe headgear to a specific application.

As shown in FIG. 7, the inner support crown 16 is of generally openframe crown shape, and includes an annular portion 70 and arcuateportions 72 which extend upwardly therefrom and are integral at theirlower ends to the portion 70 at circumferentially spaced points thereon.At their upper ends the arcuate portions 72 are integral with each otherso as to provide a relatively large portion 74 in the support crown 16which overlies the vertex 50 and the parietal brain area 51. As shown inFIGS. 10 and 12, the support crown portions 70 and 72 are of a cellularconstruction. The portion 70 has an inner wall 76 curved to conform tothe shape of the wearers head, an outer wall 78 and an inner partition80, which is of increased thickness relative to the walls 76 and 78 andforms a pair of inflated chambers or cells 82 and 84 in the portion 70.Likewise, each arcuate portion 72 has its inner wall 86 curved toconform to the shape of the wearers head, an outer wall 88, and an innerpartition 90 which coacts with the walls 86 and 88 to form internalinflated chambers or cells 92 and 94. The cells in the portions 70 and72 communicate as shown in FIG. 6, at the junctures of the portions 70and 72 so that air or inert gas can flow therebetween to distributeforces throughout the support crown 16.

The inner support crown 16 is positioned against the inner surface 18 ofthe outer shell 14 and is removably secured thereto in a suitablemanner. In the illustrated embodiment of the invention, a plastic hookand loop assembly 96 (FIG. 9), of well known type, is utilized to securethe support crown portion 70 to the shell portion 24. The assembly 96includes a pair of plastic tapes 98 and 100 secured, by suitableadhesives, molded-in, or heat sealed, to the inner surface of the shellportion 24 and the outer wall 78 of the support crown portion 70,respectively. One of the tapes contains a myraid of tiny nylon loops andthe other tape contains a similar number of tiny hooks. One suitableproduct of this type is marketed by Charles Mayer Studios, Inc. ofAkron, Ohio, under the name Hook N Loop. As shown in FIG. 9, the tapes98 and 100 readily adhere to each other, by virtue of the hooks andloops therein, when the tapes are pressed against each other. As shownin FIG. 10, the tape 100 can be readily disengaged from the tape 98,which makes removal of the inner support crown from the outer shell asimple operation and thereby permits ready cleaning and sanitation ofthe protective headgear assembly. This type of fastening assures fullcontact of the exterior surface of the vertical wall circumferentiallyaround the bottom of the inner support crown. This feature also makes itpossible to use various sizes of inner support crowns with but one sizeouter shell being required.

FIGURES 11 and 13 illustrate a modified form of the inner support crown16 in which the annular and arcuate portions 70a and 72a, correspondingto the portions 70 and 72, are formed with two internal partitions so asto form three chambers or cells 102, 104 and 106 in the portion 70a andsimilar cells 108, 110 and 112 in the portion 720:. Such a constructionis illustrated to indicate that more than two cells can besatisfactorily employed in each inner support crown portion.

The inner support crown 16 is preferably formed to a one piececonstruction by a suitable rotational molding process so as to form afail-safe (i.e., incapable of deflation or collapse of all cell portionssimultaneously under stress conditions.

Impact absorbing multicellular inflatable temporal, aural and mandibularelements, one of which is indicated at 111, FIG. 8, are formed of ayieldable resilient material, and in a preferred embodiment of theinvention this material is vinyl plastisol. As shown in FIG. 8, theseelements are of cellular construction. The inner wall 113 is shaped tofit the mandibular of the wearer, the outer wall 114 conforms to theinside contour of vertical side portion 52 of the outer shell 14, theinside surface 116 provides clearance around the external ear, theoutside surface 115 is shaped to the outer edge of side portion 52 andthe upper surface lies adjacent the bottom surface of section 70 of theinner support crown. The inner wall 113, partition 107, outer wall 114,inner surface 116 and top surfaces 117 form a pair of inflated cells 118and 119. The temporal, aural and mandibular elements are secured byplastic hook and loop so as to extend in contiguity with the innersurfaces of the vertical side portions 52 of the outer shell 20'.

With the inner support crown 16 attached to the shell 14, as shown inFIGS. 9 and 10, blows applied to the outer shell 14 have the energytherein absorbed in various degrees in the cells 82, 84, 92 and 94.These cells can be placed under pressure by employing a needle and heatseal to inject air or inert gas into the cells prior to use of theheadgear 10 so as to obtain the desired degree of energy absorption in aheadgear designed for a specific purpose.

The cells in the inner support crown 16 react instantaneously to absorbthe force energy. When an impact force is applied to one of theresilient sections 22 in the shell 14 the impact is instantly partiallyabsorbed by deforming of the section 22, with any over pressure forcebeing quickly distributed to adjacent firm sections 20 for furtherdistribution and transmission to the impact absorbing multicellularinner support crown 16 which again instantaneously reacts to distributeand absorb the force applied. One important advantage of the innersupport crown 16 is that it can readily be deflated by piercing with asharp pointed instrument or tool to facilitate removal of the entireprotective headgear assembly in cases of severe internal and externalhead, membrane, dental and cervical spine and spinal cord injuries.

As shown in FIG. 1 and FIG. 2, the impact absorbing inflatable chin cup58 and integral adjustable and selfretractable chin strap 59 are formedof a yieldable resilient material, and in a preferred embodiment of theinvention this material is vinyl plastisol. As shown in FIG. 2, the chincup is of a cellular construction. The inner wall 60 is compound curvedto conform to the shape of the wearers chin 13 and an outer wall 61 andan inner partition 62, which is of increased thickness relative to thewalls 60 and 61 forms a pair of inflated cells 66 and 67. The upper wall63 and lower wall 64 taper in plain form at the sides of the chin cup soas to become integral with the inner wall 60, the partition 62 and theouter wall 61 which also taper as they wrap around the chin to form theintegral chin strap 59 at a point 65 just forward of the front edge ofside section 52 of the outer shell firm section 20. Suitable metalfasteners are used to attach the adjustable and self-retractable chinstrap 59 to the mating fastener anchored to the side section 52 andthereby make it possible to quickly secure the protective headgear inposition on ones head. Although the protective headgear in normal use isheld firmly in position by a properly adjusted chin strap, it can belifted upward and backward without applying severe shock forces to thecervical spine as other present rigid chin cups and chin straps do.

The modified form of headgear assembly indicated at 120, in FIG. 14, isan adaptation of the assembly for use by construction workers and thelike. The assembly 120 includes an outer shell 122 having a metalsection 124 at the top of the wearers head, a brim section 126,similarly formed of metal, and resilient sections 128 which are securedto and extend between the sections 124 and 126. The sections 124 and 126correspond to the firm section in assembly 10 and the sections 128correspond to the resilient sections 22. In the protective headgearassembly 120, the resilient sections 128 are secured to the section 124and 126 by means of internal flanges 130. An inner support crown 16 likethat previously described is secured by a hook and loop assembly 96circumferentially to the inner surface of the shell 122, exactly as inthe assembly 10.

From the above description, it is seen that this invention providesimproved protective headgear assemblies which effectively prevent braininjury by virtue of the unique construction and assembly of the outershell 14 and the resilient inner support crown 16.

We claim:

1. In a protective headgear assembly, an outer shell shaped to overlie ahuman head, said outer shell being formed with a firm section of lowresilience and sections of relatively greater resilience, said firmsection including a first annular portion adapted to be disposed in ahorizontally inclined position on a wearers head, a second portion ofarcuate strip shape extending fore and aft of said shell and having apair of ends connected to substantially diametrically opposite areas ofsaid first portion, third portions secured to said strip portionintermediate the ends thereof and extending downwardly and forwardlytherefrom, said third portions being secured at the lower ends thereofto said first portion, said resilient sections being of arcuatesubstantially quadrant shape and being located in said shell atpositions bounded by said first, second and third portions.

2. In a protective headgear assembly having the structure according toclaim 1 wherein said outer shell is of one piece plastic construction,said firm section being of increased thickness relative to the thicknessof said sections of greater resilience.

3. A protective headgear assembly according to claim 1 further includingan inner support positioned within said outer shell insurface-to-surface engagement therewith, said inner support being formedof a yieldable resilient material and including a hollow annular sectiondisposed within said annular portion of said outer shell, partitionmeans in said annular section forming a plurality of side-by-sidechambers, and a plurality of hollow arcuate sections secured tocircumferentially spaced portions of said annular section and extendingupwardly therefrom into said outer shell so as to form an open generallycrown shape structure.

4. A protective headgear assembly according to claim 3 further includingpartition means in each of said arcuate sections forming a plurality ofchambers in said arcuate sections which communicate with said chambersin said annular section.

5. A protective headgear assembly according to claim 1 wherein the loweredge of said annular portion of the outer shell is located so that it isin a clearance relation with the cervical spine of the wearer at theback of the wearers head.

6. A protective headgear assembly according to claim 3 further includinga chin cup formed of a yieldable resilient material shaped to include ahollow section conforming to the shape of the chin of a wearer,partition means in said chin section forming a plurality of enclosedcells arranged in a side-by-side relation in a direction extendingoutwardly from the wearers chin and strap means connecting said chinsection to said outer shell.

7. In a protective headgear assembly, a relatively rigid outer shell,means forming a first fluid filled hollow chamber disposed inwardly ofand spaced from said outer shell so as to be located between said outershell and the head of a wearer, and means forming a second fluid filledhollow chamber disposed between said outer shell and said first chamberand operable to transmit forces from said outer shell to said firstchamber.

8. A protective headgear assembly according to claim 7 wherein saidchambers are formed in an inner crown support positioned within anddisposed in engagement with said outer shell, said inner crown supportcomprising a hollow annular section formed of a yieldable resilientmaterial, partition means in said annular section forming said chambers,a plurality of hollow arcuate sections secured to circumferentiallyspaced portions of said annular section and extending upwardlytherefrom, and partition means in said arcuate sections forming saidchambers.

References Cited UNITED STATES PATENTS 1,072,321 9/1913 Fitch 232,140,716 12/1938 Pryale 23 2,618,780 11/1952 Cushman 23 2,632,1733/1953 Lyon.

2,717,384 9/1955 Frothingham 23 2,867,811 1/1959 Jones 29 XR 3,186,0046/1965 Carlini 23 3,344,433 10/1967 Stapenhill 23 JAMES R. BOLER,Primary Examiner

